This invention relates to a sealing composition for concrete and more particularly, to a water dispersible sealing composition for protecting concrete against spalling, cracking or other deterioration caused by the penetration of water through exposed concrete surfaces.
Concrete used in the concrete industry for constructing and repairing pavements, highways, buildings, and the like are typically coated with a sealing composition to prevent or inhibit the penetration of water through exposed surfaces in order to inhibit or prevent the water from damaging the concrete. Water penetration is of particular concern in areas where temperatures may fluctuate between freezing and thawing. Stress caused by the expansion and contraction of the water often results in low-cycle fatigue fractures in the concrete.
Equally well known in the concrete industry is the need for good curing of concrete to ensure maximizing strength characteristics. Sufficient water must be present in the concrete mix to hydrate the silicate and aluminate compounds which make up the cement. Either a deficiency or an excess of water in the mix during the curing process will result in the concrete not achieving its necessary or desired strength.
Further, such a deficiency or an excess of water may result in shrinkage thereby causing cracks to form. Therefore, formulations for making concrete normally includes only the water required for hydration. Accordingly, the rate of water loss during the curing process should be kept at a minimum. During the initial stages of curing, water evaporates at the exposed surfaces of the concrete. To prevent rapid drying, which may result in shrinkage and cracking of the concrete, sealing compositions are often used to coat freshly laid concrete to inhibit or prevent such evaporation.
One concrete sealing composition typically used in the concrete industry to inhibit or prevent water penetration through exposed concrete surfaces comprises a high concentration of refined oil such as petroleum oil. The use of petroleum based oils, however, may cause surface discoloration. Another concrete sealing composition typically used in the concrete industry comprises a high concentration of linseed oil. The use of a linseed oil, however, also results in surface discoloration. In addition, such concrete sealing compositions often use petroleum based solvents or carriers to reduce viscosity for application. Since spraying is a common method of applying water sealing compositions for concrete, sealing compositions containing petroleum based oils, solvents or carriers have been criticized since prolonged breathing of the spray mist can result in health problems. The use of such sealing compositions has also been criticized because of their general high degree of flammability and the potential for environmental problems caused by spillage, run off and over spray.
Sealing compositions have been developed which use refined vegetable oils and silicone oil dispersants. Such sealing compositions are relatively easy to apply and do not have many of the concerns associated with petroleum based oil compositions. However, they generally deteriorate quickly and, depending on the weather conditions, must be reapplied every five or six months.
Other sealing compositions typically used in the concrete industry for inhibiting or preventing the penetration of water through exposed concrete surfaces contain a chlorinated rubber or a chlorinated resin. Such sealing compositions, however, are susceptible to ultraviolet destruction and rubber marking caused by automobile and truck tires.
Consequently, a need exists for a sealing composition for concrete which is effective for preventing or inhibiting the penetration of water through exposed surfaces in order to protect against spalling, cracking or other deterioration caused by such penetration of water and which is non-toxic, non-staining, stable, ecologically acceptable, relatively inexpensive and easily applied.